Frost dates by ZIP code: The nearest NOAA stations to your ZIP, 1991-2020 normals
Enter a five-digit ZIP code. PlainClimate finds its center (Census Bureau 2024) and the five nearest NOAA stations with frost dates, and shows each station's last spring and first autumn 32°F dates with its distance and elevation.
Frost dates near ZIP 77340
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 77340 in zone 9a (the coldest night of a typical year: 20 to 25°F).
The nearest station, Huntsville station, TX, is 4 miles from the ZIP's center: its last spring frost comes after March 1 in half of years and after March 22 in one year in ten. By the USDA's method its plant hardiness zone is 9a.
| Station | Distance | Elevation | Last frost (median) | 1 in 10 after | First frost (median) | Hardiness zone |
|---|---|---|---|---|---|---|
| Huntsville station, TX | 4 mi | 494 ft | March 1 | March 22 | November 28 | 9a |
| Huntsville, TXHuntsville Municipal Airport | 7 mi | 366 ft | March 2 | March 24 | November 26 | 9a |
| Conroe, TXConroe Montgomery County Airport | 22 mi | 245 ft | March 11 | April 3 | November 19 | 9a |
| Conroe station, TX | 23 mi | 245 ft | February 24 | March 17 | December 2 | 9a |
| Madisonville, TX | 30 mi | 252 ft | March 16 | April 7 | November 11 | 8b |
Frost comes later in spring at higher and colder stations and earlier in low, open ground: prefer a station at a similar elevation to yours. Hardiness zone in the table: the USDA's rule (the average of each year's coldest night, 1991-2020) applied to the station's own record.
Every frost threshold at Huntsville station
NOAA publishes the dates for several temperatures and odds. A 30% spring date means a 3-in-10 chance of a later frost (the convention almanacs use); 50% is the median; 10% the cautious date.
| Threshold | Spring, 10% | Spring, 30% | Spring, 50% | Spring, 90% | Autumn, 50% | Autumn, 10% |
|---|---|---|---|---|---|---|
| 36°F (light frost) | April 3 | March 22 | March 14 | February 21 | November 16 | November 1 |
| 32°F | March 22 | March 10 | March 1 | February 2 | November 28 | November 6 |
| 28°F (hard freeze) | March 11 | February 26 | February 12 | January 13 | December 13 | November 19 |
| 24°F | March 2 | February 10 | January 29 | December 27 | January 1 | December 1 |
Source: NOAA NCEI 1991-2020 annual normals; ZIP centers: Census Bureau 2024 Gazetteer; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026. Autumn 10%: one year in ten has its first frost before this date.